Acoustic control system having alternate enabling and control signal

ABSTRACT

A control system utilizing an acoustic link between a transmitter and a receiver and operating upon signals having a unique coding format. The transmitter generates and transmits an acoustic coded signal which comprises a plurality of space tones of one frequency, and a data tone of a different frequency between successive space tones. The receiver includes an input circuit that receives the transmitted coded signal and responds to the space tone to provide an enabling signal, and detecting and decoding means which is connected to the input means and rendered operative in response to the enabling signal to detect and decode the data tones to provide a control signal for controlling a remote device when a proper sequence of data signals is decoded.

United States Patent 1 91 Carman 1 1 June 5, 1973 [54] ACOUSTIC CONTROL SYSTEM 3,040,298 6/1962 Thomas ..340/14s x HAVING ALTERNATE ENABLING AND 3,233,503 3/1966 Ultermark 340 171 PF CONTROL SIGNAL Primary ExaminerHarold I. Pitts [75] Inventor: Richard J. Carman, Houston, Tex. w Hyerv Marvin B Eickemohh [73] Assignee: Cameron Iron Works, In Jfiflnings E. Thompson and Robert W. Turner Houston, Tex.

[57] ABSTRACT [22] Filed: Apr. 19, 1972 A control system utillzlng an acoustic link between a PP 245,582 transmitter and a receiver and operating upon signals having a unique coding format. The transmitter Relmed Application Data generates and transmits an acoustic coded signal [63] Continuation f s 38,7, May 19, 1970 which comprises a plurality of space tones of one abandone frequency, and a data tone of a different frequency between successive space tones. The receiver includes 52 0.5. CI ..340/l48 R, 340/171 PF an it1Put circuit that receives the transmitted coded 511 Int. Cl. ..l-l04g 5/00 Sign! and resrmds I0 Space Provide 581 Field of Search ..340/I48 R 171 R enabling signal and wading afld dewding means which is connected to the input means and rendered [56] References Cited operative in response to the enabling signal to detect and decode the data tones to provide a control signal UNITED STATES PATENTS for controlling a remote device when a proper sequence of data signals is decoded. 2,811,708 l0/l957 Byrnes ..340l17l PF 16 Claims, 3 Drawing Figures /f 6 /5 m 5 g (MM COD/N6 mpg/ 1 aw Pan/[4 (GA/J01! 106/6 AMP. a '9 @2 52? 2 l /!i 7041f OJC/l-JW xnm aewk. 106/:

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2 Shasta-Sheet 2 ACOUSTIC CONTROL SYSTEM HAVING ALTERNATE ENABLING AND CONTROL SIGNAL CROSS-REFERENCE TO RELATED APPLICATIONS This is a continuation of patent application Ser. No. 38,761 filed May 19, I970 and entitled ACOUSTIC CONTROL SYSTEM now abandoned.

BACKGROUND OF THE INVENTION Field of the Invention and Prior Art The control system described in this invention finds useful application in offshore drilling operation. More specifically, in offshore petroleum recovery operation (as well as other operations in hostile environments), there are many disadvantages and dangers in the equipment presently utilized. For example, the present equipment utilizes hydraulically controlled subsea valves and similar devices. This equipment necessitates a plurality of hoses and cables depending from the surface rig or platform to the sub-surface equipment. These hoses and cables are relatively expensive. Moreover, the hoses and cables are difficult to maintain under normal conditions. These problems are magnified and intensified in storm operations.

Furthermore, if the cables become defective or broken, or the like, the interface between the surface and sub-surface unit is destroyed and control of the subsea equipment is impossible.

The disadvantages of a hydraulic or electrohydraulically controlled system (i.e., with electrical cables to the subsea equipment) are severe enough in relatively shallow water, e.g., up to about I50 feet. However, the areas of offshore activity in such shallow water are rapidly becoming fully exploited whereby petroleum producers are being forced to explore and exploit subsea areas which are at much greater depths, such as 600 feet or more. In these depths, all of the aforementioned problems are magnified and intensified severalfold. Moreover, at great depths, it is relatively impossible, or at least impractical, to utilize human divers.

Therefore, it becomes imperative to utilize another approach to controlling the subsea equipment for offshore wells. Some progress has been made in this direction as witnessed by the subsea control systems de- SUMMARY OF THE INVENTION The subject invention relates to an acoustically controlled system. The invention comprises a system which includes at least a transmitter and a receiver. The transmitter includes a suitable command console which produces signals which are properly coded and transmitted to the subsea receiver. The subsea receiver includes a tone detector and a power switching circuit which selectively energizes the tone detector and a logic decoder whereby the signals produced by the transmitter are received and decoded. The utilization device, such as a subsea valve or the like, receives the signal from the decoder and performs the appropriate function.

More particularly, the system uses a novel code arrangement and signal format. This novel code and sig nal format permits the transmitter and receiver to perform in a coordinated manner. The transmitter produces signals of a specified type. The receiver is operative to detect specified signals, reject unspecified signals and substantially eliminate undesirable operations by spurious signals which are produced and detected in subsea environments. Moreover, reliable operation is achieved because the system is self-synchronizing regardless of the environmental conditions.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, wherein like reference characters are used throughout to designate like parts:

FIG. 1 is a block diagram of the control system show ing a transmitter and a receiver.

FIG. 2 is a block diagram of the receiver circuit portion of the system shown in FIG. 1.

FIG. 3 is a schematic representation of the signal and code format utilized by the instant invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. I, a suitable command console 10 is connected to coding logic circuit 11. Command console 10 may be any suitable type of console which includes a plurality of switches or the like which are manually controlled. Console 10 can be representative of a computer or the like which provides overall supervisory control of the production system.

Coding logic circuit 11 is a suitable circuit which receives signals from command console 10 and operates upon these signals to identify, in a coded format, the function and devices which are to be operated in accordance with the signals produces by command console 10. Coding logic circuit 11 produces digital output signals which are representative of the input signals. Thus, logic circuit 11 converts the signals supplied by console 10 to a compatible format for use by the remainder of the receiver circuit. Logic circuit 11 may include integrated circuits or discrete components as is necessary or desirable.

Oscillator/FSK Generator I3 is a suitable circuit for producing signals of a predetermined frequency or frequencies. In one embodiment, the oscillator circuit includes at least one crystal controlled oscillator. Moreover, the oscillator circuit may produce more than one signal frequency to represent different types of information. For example, the input signals supplied by con sole [0 may have different informational significance. Thus, different frequencies are required to convey this information. The information is represented by frequency shift keyed (FSK) tones and supplied to transmitter logic circuit 12.

Transmitter logic circuit 12 receives tone signals from generator 13 and control signals from coding logic circuit 11. In effect, the tone signals are applied continuously to transmitter logic circuit 12. The digital type signals from coding logic circuit 11 are selectively applied to transmitter logic circuit 12. Transmitter logic circuit 12 operates to selectively transmit tone signals therethrough as a function of the digital signals from coding logic circuit 11.

in addition, transmitter logic circuit 12 controls the timing of operation in coding logic circuit 11. This control is effected by supplying control signals to circuit 11 as a function of internal operation of circuit 12. In this manner, internal synchronization in the transmitter network is achieved.

The output of transmitter logic circuit 12 is supplied to power amplifier 14. Power amplifier 14 is a suitable amplifier circuit which operates to amplify the signals supplied thereto. That is, the low power tone signals transmitted by logic circuit 12 are supplied to trans ducer 15 at suitable power to drive the transducer. The transducer is any suitable projector or similar transducer which is adapted to produce acoustic signals which will be transmitted through the environmental medium such as water or the like.

Hydrophone 16 is the subsurface receiving transducer which detects signals produced by hydrophone l5. Hydrophone 16 is connected to supply an input to low current receiver circuit 17. Receiver circuit 17 includes a bandpass amplifier which receives the low level output signal from hydrophone l6. Receiver circuit l7 amplifies (or limits) the signals from hydrophone 16 to a sufficient level to operate the circuits included in power switching network 18 and tone detector 19. In a preferred embodiment, receiver circuit 17 includes an automatic gain control network whereby a constant output signal level is supplied independent of the input signal level.

Tone detector circuit 19 receives the signals from low current receiver circuit 17. Tone detector circuit 19 includes a suitable number of tone filter circuits for detecting the signals transmitted by the transducers. For the code format employed in the instant embodiment, tone detector circuit 19 may include tone filters for detecting a binary 1, binary 0, or a space tone signal. The binary l and 0 signals represent data signals and are produced by different tone frequencies. The space tone is a different frequency tone and provides a timing and logic function.

The output on tone detector circuit 19 is connected to an input of power switching circuit 18. With the application of appropriate signals to tone detector 19, power switching circuit 18 is energized and produces an output signal which is returned to tone detector 19 for activation of other circuitry in the tone detector. The operation of power switching circuit 18 is dependent upon the signals supplied thereto by tone detector 19. Thus, the power switching circuit operation is selectively controlled. By this type of operation, the current drain on the subsea system is relatively small whereby power requirements are reduced.

When tone detector 19 receives the appropriate output signal from power switching circuit 18, tone detector 19 is further activated. Thus, at this point, tone detector 19 can produce output signals as a result of the data tone signals supplied by low current receiver 17 to the tone detector circuit.

Outputs of tone detector circuit 19 and power switching circuit 18 are supplied to inputs of logic decoder 20. The signals supplied to logic decoder 20 are representative of the data signals detected by tone detector 19. Logic decoder 20 operates upon the data signals supplied thereto and produces appropriate output signals which determine the specific underwater device to be operated and the function to be performed by that device. An automatic reset signal is supplied to logic decoder 20 by power switching circuit 18 shortly after power switching circuit 18 is energized so that logic decoder circuit 20 is automatically set to prescribed initial conditions. In essence, power switching circuit 18 includes a timing network which must be up dated by an appropriate signal from tone detector 19 in order to prevent the production of a "timeout sig nal." In the absence of such an updating signal, power switching circuit 18 is automatically reset to a non operative condition whereby the receiver is inoperative and spurious signals in the underwater environment or hydrospace do not cause inappropriate operation thereof. The output oflogic decoder 20 is connected to utilization device 21. Utilization device 21 may be any suitable underwater operational unit which is com trolled by signals from the logic decoder. In actual usage, utilization device 21 may represent a plurality of valves or the like which are selected and then selectively operated by decoder 20.

Transmitter 22 is connected to utilization device 21 to receive signals therefrom. Thus, transmitter 22, an optional feature in this invention, may transmit feedback signals to the surface which feedback signals represent the condition of the utilization device. Transmitter 22 is substantially identical to the transmitter circuit previously described. Receiver 23, which is similar to the receiver circuit described supra, receives signals from transmitter 22. Receiver 23 is connected to command console 10 to produce signals thereat whereby the operator is informed of the status at the underwater utilization device.

Referring now to H0. 2, there is shown a more detailed block diagram of the receiver circuit. In FIG. 2, components which are similar to components shown and described in FIG. I bear similar reference numerals.

Thus, hydrophone 16 is connected to an input of low current receiver 17. The output of low current receiver 17 is supplied to tone detector 19 shown in dashed outline. More particularly, the output of low current receiver 17 is connected to the inputs of three separate tone filters 50,51 and 52. Tone filter 50 is a specially designed circuit which is utilized to detect a "space" tone. A space tone is defined as a signal tone which is utilized between data tones as shown in the representa tion shown in FIG. 3. The space tone may be consid ered to be an identifying tone which signifies that useful data follows thereafter. As will be seen hereinafter, a space tone operates as an enabling signal for the receiver signal circuit. Thus, the space tone effects synchronization as well as improving reliability.

Tone filter 51 is a specially designed circuit which detects a suitable "data" tone (see FIG. 3) which is representative of a suitable signal, for example, a binary 1. Tone filter 52 is another specially designed circuit which detects a data tone which is representative of a suitable signal such as a binary O. The output of tone filter 51 is connected to the set input of set-reset flipflop 54. Flipflop 54 is designated as FF A. The output of tone filter 52 is connected to the set input of setreset flipflop 53 which is designated as FF B.

The output of tone filter 50 is connected to the set input of power switch 58. Power switch 58, along with a suitable power supply 57 and timer 72, is included in power switching circuit 18 shown in dashed outline.

The power output of power switch 58 is connected to the circuit components in the system and selectively supplies power thereto. For example, one power output of power switch 58 is connected to logic decoder and supplies a +5 volt (switched) signal thereto. Another power output of power switch 58 is connected to the circuit components of tone decoder l9 and pro vides a +l2 volt (switched) signal thereto especially including timer 72. This power triggers timer 72 into op eration. A control output of power switch 58 is connected to the automatic reset terminal of logic decoder 20 to automatically reset the circuitry therein to a suitable initial condition. Thus, it is assured that the decoder circuits are all in the proper initial state when power is supplied thereto.

The output of tone filter 50 is also connected to an input of monostable 70. The output of monostable circuit 70 is connected to the reset input of timer 72. The output of monostable 70 is further connected to the reset inputs of flipflops 53 and 54. In addition, the output of monostable 70 is connected to an input of counter 71. The output of counter 71 is connected to the inhibit input of monostable 70.

The output of flipflop 54 is connected to an input of monostable multivibrator (mono) 55 and to an inhibit input of tone 52. The output of flipflop 53 is connected to the input of monostable multivibrator (mono) 56 and to an inhibit input of tone filter 51. The crossconnected inhibit inputs cause the respective tone filters to be rendered nonconductive and reduced multipath signal problems. The outputs of monostable circuits 55 and 56 are connected to inputs of logic decoder 20. It should be understood, that the outputs of monostable circuits 55 and 56 can be gated together within the functional block designated as tone decoder 19 or within the functional block designated as logic decoder 20 thereby supplying a serial input to logic decoder 20. For purposes of this illustration, the appropriate gating network is defined to be included within logic decoder 20. Likewise, in this embodiment, it is logic decoder 20 defined to operate in the fashion to receive serial input signals and to provide either serial or parallel output signals to utilization device 21. In a typical embodiment, logic decoder 20 operates in the serial to parallel converter mode.

Referring now to FIGS. 2 and 3 concurrently, the operation of the receiver system shown in FIG. 2 is described. Typically, a command code consists of a set of 3 distinct frequency shift keyed(FSI()tones. Two of the tones are called data tones and correspond to a binary logic I and a binary logic 0 respectively. The third tone is called a space tone and is used to provide several characteristics such as receiver synchronization, receiver power supply switching, false alarm rejection, code security and to reduce response to multipath effects. The coding sequence consists of a plurality of time slots where the number of time slots is a function of the number of operations or commands to be utilized, the number of units to be controlled and the like. In addition, a portion of the code is utilized as identifcation, for example to identify the operator or owner of the subsea equipment.

In the embodiment described herein, a code sequence having 12 time slots is utilized. Three of the time slots are used for company identification, seven for unit address and two for command functions. Obviously, as more command functions are required or desired, the code sequence could increase or the unit address or company identification must decrease. Moreover, with the binary format, an exponential relationship for the number of time slots exists. For example, in the code format described supra, eight different companies or groups could use up to I28 subsea units each and provide for four separate functions at each unit. Without changing the code format substantially, a realignment of the time slots would permit four com panies to supply four commands to 256 subsea units. Similarly, three companies would address 04 units and provide eight command functions. The specific number of time slots and the application thereof to the system is determined by the requirements of the individual user. The specific number of time slots and the allotment thereof does not form any portion of this invention, per se.

However, the concept of utilizing a space tone prior to the application of a data tone is instrumental in permitting the utilization and operation of the instant invention. The utilization of the space tone for receiver synchronization, receiver power supply switching and the like as noted supra, permits a system such as herein described to be operative with a minimum number of parts and minimal energy requirement. Typically, the operator at the surface unit will manipulate switches and the like on command console 10. Manipulation of the switches will effect specified electrical interconnections whereby suitable signals are supplied at coding logic circuit 11. Coding logic circuit 11 will operate upon the signals supplied thereto to produce other signals which are representative of the signals supplied by command console 10. Coding logic circuit 11 may include units such as a shift register, assorted logic gates and the like to convert the electrical signals from command console 10 into suitable signals for further utilization. Typically, the signals will be in the form of digital type signals or level signals which can be operated upon by other circuitry. Moreover, in a preferred embodi ment, coding logic circuit 11 converts parallel input signals into serial output signals.

The output signals from coding logic circuit II are supplied as an input to transmitter logic circuit 12. Am other input to transmitter logic circuit I2 is supplied by oscillator FSK generator 13 which supplies the three separate frequency signals to transmitter logic circuit 12. In a preferred embodiment, the frequency signals are 14.7 KHz, 15 KHz, and 15.3 KHZ respectively. Typically, the middle frequency, in this case 15.0 KHz, represents the space tone while the high and low frequencies represent the binary l and binary 0 data tones, respectively.

Transmitter logic circuit 12 includes gating networks and signal converting networks so that the tone signals from generator circuit 13 are properly transmitted as a function of the condition of coding logic circuit 11. The signal which is produced by transmitter logic circuit 12, and which is representative of the input information supplied at command console 10, is supplied to amplifier 14 for any necessary amplification prior to the ap plication to hydrophone 15.

Thus, the function defined by the operation of console 10 produces suitable logic signals from logic cir cuit 11. In addition, in accordance with the operation of logic circuit 12, appropriate tone or frequency signals supplied by generator 13 are applied to power arnplifier 14. For a detailed description of this circuit and the operation thereof, reference is made to the copending application of R. .l. Carman, entitled ACOUS- TIC CONTROL TRANSMITTER (OSl-ZJ-l9), filed on Aug. 5, 1970, bearing Ser. No. 61,339 and assigned to the instant assignee.

The signal from hydrophone 15 is transmitted to hydrophone l6 and applied to low current receiver 17. As noted, receiver 17 includes a band-pass amplifier and amplifies the signal received from hydrophone 16 to a level sufficient to drive the tone filters. An AGC or limited amplifier circuit provides a constant signal level to the tone filters independent of the signal level at hydrophone 16. The signal produced by receiver 17 is supplied to each of the tone filters 50,51 and 52 simultaneously. However, only tone filter 50 has power supplied thereto continuously. Consequently, tone filters 51 and 52 are not immediately operative when a signal is supplied by receiver 17. Provided the signal supplied thereto is of the proper frequency, tone filter 50 will be rendered operative to produce a suitable output signal. The proper frequency which renders tone filter 50 operative is, of course, the frequency previously defined as the space" tone. Thus, it is mandatory that a space tone be received to initiate operation of the receiver circuit.

When the proper space tone signal is received, tone filter 50 produces an output signal which is supplied to the set input of power switch 58. Power switch 58, which includes a set-reset flipflop, is switched whereby power supply 57 supplies power to the remainder of the receiver system. For example, a +12 volt signal is supplied to the components in the tone detector circuit 19. A volt signal is supplied to logic decoder 20.

In addition, tone filter 50 supplies a signal to mono stable 70 which operates as a single-pulser. That is, when monostable 70 is triggered, it produces a predetermined output of constant width and amplitude. Thus, for each space tone detected by tone filter 50, one and only one output signal is produced by monostable 70. Consequently, multipath signals produced in water cannot inadvertently cause operation of the receiver circuit.

Furthermore, the output signal produced by monostable 70 is supplied to timer 72. Timer 72 exhibits a time constant which is between 1 and 1% times the duration of a standard time slot. Operation of timer 72 is initiated by application of power thereto by power switch 58, as a result of the application of a space tone to tone filter 50. At this time, timer 72 produces a ramp type signal which is supplied to the reset input of power switch 58. If a space tone signal is not detected within a period of 1% time slots, timer 72 produces a signal which resets power switch 58 thereby removing power from the remainder of the circuit. Thus, if the space tone signal is the last in a sequence (or if one is missed in transmission) the receiver is shutdown and extra neous or inaccurate signals are not received.

The output of monostable 70 is connected to the reset input of timer 72. When monostable 70 changes state (i.e., the output signal switches from one level to another) timer 72 is reset to the initial condition. Thus, the output signal supplied by timer 72 is returned to the initial low level until another ramp signal is produced in response to another start signal from tone filter 50. Under normal sequencing, the output signal produced by timer 72 represents a sawtooth wave.

Counter 7] has the input thereof connected to the output of monostable 70. Each output signal produced by monostable is counted by counter 7]. At a predetermined count, an inhibit signal is supplied to monostable 70. The inhibit signal prevents monostable 70 from operating upon input signals, timer 72 will timeout" and reset power switch 58 thereby deactivating the receiver system.

Thus, monostable 70 receives sginals from tone filter 50 and produces a single output signal having a dura' tion of approximately one-half time slot duration. Timer 72 has a duration somewhat in excess ofa single time slot. Counter 71 has a count capability of a predetermined number which is dictated by the code format. Therefore, counter 71 controls when monostable 70 can and cannot operate on signals from tone filter 50. Monostable 70 controls when timer 72 is reset to the initial condition and timer 72 controls when power switch 58 connects power supply 57 to the remainder of the circuit.

With the application of the +12 volt signal to tone filters 51 and 52 via switch 58, these circuits are now rendered operative to receive and operate on the data signals supplied by receiver 17. Depending upon the frequency of the signal supplied thereto, a suitable output signal is supplied to either of filters 51 and 52. This signal is supplied to the set input of either flipflop 53 or flipflop 54. The signal supplied to fiip fiop 53 or flipflop 54 will cause the appropriate flipflop to switch states. The change in state of the flipflop will produce a change in the output signal which is supplied to one of monostable circuits 55 or 56, respectively. The monostable circuit which receives the signal is designed to produce a single output signal in response to the first detectable input signal supplied thereto. This single, constant width signal is supplied to logic decoder 20. As noted supra, by means of suitable gating logic, a binary l, or binary 0 (depending upon the data tone supplied) is stored in a suitable position in logic decoder circuit 20. This information is serially stored.

Moreover, as suggested supra, an output signal is supplied from flipflop 54 to inhibit operation of tone filter 52. Likewise an output signal from flipflop 53 is supplied to inhibit tone filter 51. This arrangement prevents a binary 1 data tone from being detected concurrently with a binary 0 data tone. By eliminating this difficulty, multipath or reverberation signals are overcome.

Thus, a signal is supplied to logic decoder 20 which is representative of a signal received at hydrophone 16. The data signals are not supplied to logic decoder 20 until the application of a space tone at low current receiver circuit 17. In addition to providing synchronization of the receiver circuit, the automatic termination of operational power switch 58 reduces the drain on the power supply. That is, unless reset by a subsequent space tone, the circuit remains inactive.

1n continuous operation, for example when a suitable code word is being received, the space tone will operate the power switch and the fiipflops as noted supra. The data tones will be received by the appropriate tone filters and supplied to logic decoder 20. In addition, upon detection of a data tone by one of the tone filters, the associated flipflop assumes the set condition and will not detect additional signals from the tone filter until reset. Furthermore, the cross-coupled fiipflops inhibit the counterpart tone filters. Thus, spurious noise or random signals in the environment cannot supply erroneous signals which would trigger the other tone filter to produce an erroneous condition.

Thus, there has been described an acoustic control system utilizing a preferred coding arrangement and having both a transmitter and receiver which are especially effective with the specified code/signal format. The code/signal format and the components which are utilized therewith offer advantages in synchronization, low power drain, secure coding and high reliability. It is understood that certain modifications may be made to the specific structure of the components in the receiver and transmitter units. However, any modifications made to the system as described and which fall within the purview of the invention are meant to be included in this description.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth (or shown in the accompanying drawings) is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed l. A remote control system comprising, in combination: transmitting means for generating and transmitting a coded control signal providing a plurality of distinctive space signals and a plurality of distinctive data signals in a predetermined sequence, with a data signal being provided between successive space signals; and receiving means adapted to be remotely located from said transmitting means for receiving and responding to said coded control signal, said receiving means including input means for receiving said coded control signal and responsive to received space signals to provide an enabling signal, and detecting and decoding means connected to said input means and rendered operative in response to said enabling signal for detecting and decoding said data signals.

2. The control system of claim 1 wherein said transmitting means generates and transmits a predetermined number of said space signals as a part of said coded control signal and said receiving means further includes counter means connected to said input means for counting each of said space signals when received, said counting means generating an inhibit signal when said predetermined number of space signals are counted for rendering said detecting and decoding means inoperative until generation of another enabling signal by said input means.

3. The control system of claim 1 wherein said transmitting means generates and transmits successive space signals of said coded control signal at predetermined intervals and wherein said receiving means further includes delay means connected to said input means and responding to said enabling signal for generating a delay signal having a duration at least as great as the interval between successive space signals of said coded control signal, and power switch means connected to said input means, said delay means and to said detecting and decoding means, said power switch means adapted to be connected to a source of electrical energy and responsive to said enabling signal to cause conduction of electrical energy from said source to said detecting and decoding means to render it operative, said power switch means also responsive to said delay signal to stop the conduction of electrical energy to said detecting and decoding means and render it inoperative when a space signal is not received by said receiving means during the duration of said delay signal.

4. The control system of claim 3 wherein said delay means includes a timer circuit connected to said power switch means, said timer circuit providing said delay signal in response to said enabling signal, and a monostable circuit connected between said input means and said timer circuit and responsive to received space signals to reset said timer circuit prior to the end of said delay signal.

5. The control system of claim 1 wherein said transmitting means generates and transmits said coded control signal as an acoustic signal including a predetermined number of successive time slots of a predetermined time interval, with each time slot including a space signal of one acoustic frequency followed by a data signal of at least one other acoustic frequency, and said input means includes space signal filter means tuned to the frequency of said space signal and said detecting and decoding means includes at least one data signal filter means tuned to the frequency of said data signal.

6. The control system of claim 5 wherein the combination of transmitted data signals of said coded control signal provide a binary code and binary l of said code is represented by a data signal of one of said other fre quencies and binary 0 is represented by a data signal of another of said other frequencies and said detecting and decoding means includes two data signal filters each tuned to the frequency of one of said data signals, and further including means connected between said data signal filters for inhibiting the operation of one of said data signal filters when the other data signal filter is providing an output in response to receipt of its respective data signal.

7. The control system of claim 3 wherein each space signal is transmitted at one acoustic frequency and is followed by a data signal of at least one other acoustic frequency, and said input means includes space signal filter means tuned to the frequency of said space signal and said detecting and decoding means includes at least one data signal filter means tuned to the frequency of said data signal.

8. The control system of claim 7 wherein the combination of transmitted data signals of said coded control signal provide a binary code and binary l of said code is represented by a data signal of one of said other acoustic frequencies and binary 0 is represented by a data signal of another of said other acoustic frequencies, and said detecting and decoding means includes two data signal filters each tuned to the frequency of one of said data signals, and further including means connected between said data signal filters for inhibiting the operation of one of said data signal filters when the other data signal filter is providing an output in response to receipt of its respective data signal.

9. The control system of claim 8 wherein said last mentioned means includes first and second flipflop means each having one input connected to said input circuit and responsive to said enabling signal to be switched to a reset state, another input of said first flipflop means connected to the output of one of said data signal filter means, and another input of said second flipflop means connected to the output of said other data signal filter means, and wherein said detecting and decoding means further includes a decoder logic circuit for decoding the binary code represented by said data signals to provide an output signal for controlling an utilization device, and circuit means connecting the output of said first and second flipflop means to said decoder logic circuit,

10. An acoustic control system comprising, in combination: transmitting means including signal generator means for providing a plurality of different acoustic sig nals, coding logic means for providing coded logic pulses in response to an operator command, combining means connected to said signal generator means and said coding logic means and responding to said coded logic pulses and said different acoustic signals to pro vide a coded control signal comprising said plurality of different acoustic signals in a coded sequence, and transmitting transducer means connected to said combining means for radiating said coded control signal including said different acoustic signals; and receiving means including an input circuit having receiving transducer means for receiving and responding to said radiated coded control signal, detecting means including a plurality of distinctive signal detecting circuits connected to said input circuit and each detecting circuit detecting and responding to one of said different acoustic signals of said coded control signal output signals, at least one of said detecting circuits adapted to be connected to a source of electrical energy to be normally operative and responding to the first received of said different acoustic signals comprising said coded control signal to provide an enabling signal, the remaining detecting circuits being normally in a stand-by condition, decoding means connected to said detecting means for decoding and acting on the coded control signal when detected by said detecting means, and power switch means adapted to be connected to a source of electrical energy and connected to said detecting means and said decoding means, said switch means responsive to said enabling signal to supply electrical energy to activate said decoding means and said remaining of said detecting circuits.

11. The control system of claim 10 wherein said sig nal generating means provides said plurality of different acoustic signals at different audio frequencies, one of said different frequency signals representing a space tone and at least one other of said output signals representing a data tone; said combining means responds to said coding logic means to provide said coded control signal with a predetermined number of said space tones being transmitted at predetermined time intervals and with at least one data tone transmitted between successive space tones, and wherein said at least one of said detecting circuits is a space tone filter circuit tuned to substantially the frequency of said space tone, and each of said remaining of said detecting circuits is a data tone filter circuit tuned to substantially the frequency of a data tone,

12. The control system of claim 11 wherein said coded control signal provides a binary code and two data tones of different frequencies are transmitted to represent respectively binary l and binary 0, and said detecting circuits comprises two data tone filter circuits each tuned to substantially the frequency of one of said data tones.

13. The control system of claim 12 further including inhibit means connected between said data tone filter circuits for inhibiting the operation of one of said data tone filter circuits when the other data tone filter circuit is producing an output in response to receipt of its respective data tone.

14. The control system of claim 11 further including delay means connected to said detecting means and to said power switch means, said delay means responsive to said enabling signal to generate a delay signal having a duration at least as great as the interval between successive space tones, said power switch means responsive to said delay signal to stop the conduction of electrical energy to said decoder means and said data tone filter circuits to render them inoperative when a space tone is not received by said receiving means during the duration of said delay signal.

15. The control system of claim 14 wherein said delay means includes a timer circuit connected to said power switch means, said timer circuit providing said delay signal in response to said enabling signal, and a monostable circuit connected between said space tone filter circuit and said timer circuit and responsive to re ceived space tone signals to reset said timer circuit prior to the end of said delay signal.

16. A remote control system, comprising, in combi nation: transmitting means including signal generator means for providing a plurality of different signals, coding logic means for providing coded logic pulses in response to an operator command, combining means connected to said signal generator means and said coding logic means and responding to said coded logic pulses and said different signals to provide a coded control signal comprising said plurality of different signals in a coded sequence, and transmitting transducer means connected to said combining means for radiat ing said coded control signal; and receiving means including an input circuit having receiving transducer means for receiving and responding to said radiated coded control signal, detecting means including a plurality of distinctive signal detecting circuits connected to said input circuit and each detecting circuit detecting and responding to one of said different signals of said received coded control signal, at least one of said detecting circuits adapted to be connected to a source of electrical energy to be normally operative and responding to the first received of said different signals comprising said coded control signal to provide an enabling signal, decoding means connected to said detecting means for decoding and acting on the coded control signal when detected by said detecting means, and power switch means adapted to be connected to a source of electrical energy and connected to said detecting means and said decoding means, said switch means responsive to said enabling signal to supply electrical energy to activate said decoder means and at least part of said detecting means.

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1. A remote control system comprising, in combination: transmitting means for generating and transmitting a coded control signal providing a plurality of distinctive space signals and a plurality of distinctive data signals in a predetermined sequence, with a data signal being provided between successive space signals; and receiving means adapted to be remotely located from said transmitting means for receiving and responding to said coded control signal, said receiving means including input means for receiving said coded control signal and responsive to received space signals to provide an enabling signal, and detecting and decoding means connected to said input means and rendered operative in response to said enabling signal for detecting and decoding said data signals.
 2. The control system of claim 1 wherein said transmitting means generates and transmits a predetermined number of said space signals as a part of said coded control signal and said receiving means further includes counter means connected to said input means for counting each of said space signals when received, said counting means generating an inhibit signal when said predetermined number of space signals are counted for rendering said detecting and decoding means inoperative until generation of another enabling signal by said input means.
 3. The control system of claim 1 wherein saiD transmitting means generates and transmits successive space signals of said coded control signal at predetermined intervals and wherein said receiving means further includes delay means connected to said input means and responding to said enabling signal for generating a delay signal having a duration at least as great as the interval between successive space signals of said coded control signal, and power switch means connected to said input means, said delay means and to said detecting and decoding means, said power switch means adapted to be connected to a source of electrical energy and responsive to said enabling signal to cause conduction of electrical energy from said source to said detecting and decoding means to render it operative, said power switch means also responsive to said delay signal to stop the conduction of electrical energy to said detecting and decoding means and render it inoperative when a space signal is not received by said receiving means during the duration of said delay signal.
 4. The control system of claim 3 wherein said delay means includes a timer circuit connected to said power switch means, said timer circuit providing said delay signal in response to said enabling signal, and a monostable circuit connected between said input means and said timer circuit and responsive to received space signals to reset said timer circuit prior to the end of said delay signal.
 5. The control system of claim 1 wherein said transmitting means generates and transmits said coded control signal as an acoustic signal including a predetermined number of successive time slots of a predetermined time interval, with each time slot including a space signal of one acoustic frequency followed by a data signal of at least one other acoustic frequency, and said input means includes space signal filter means tuned to the frequency of said space signal and said detecting and decoding means includes at least one data signal filter means tuned to the frequency of said data signal.
 6. The control system of claim 5 wherein the combination of transmitted data signals of said coded control signal provide a binary code and binary 1 of said code is represented by a data signal of one of said other frequencies and binary 0 is represented by a data signal of another of said other frequencies and said detecting and decoding means includes two data signal filters each tuned to the frequency of one of said data signals, and further including means connected between said data signal filters for inhibiting the operation of one of said data signal filters when the other data signal filter is providing an output in response to receipt of its respective data signal.
 7. The control system of claim 3 wherein each space signal is transmitted at one acoustic frequency and is followed by a data signal of at least one other acoustic frequency, and said input means includes space signal filter means tuned to the frequency of said space signal and said detecting and decoding means includes at least one data signal filter means tuned to the frequency of said data signal.
 8. The control system of claim 7 wherein the combination of transmitted data signals of said coded control signal provide a binary code and binary 1 of said code is represented by a data signal of one of said other acoustic frequencies and binary 0 is represented by a data signal of another of said other acoustic frequencies, and said detecting and decoding means includes two data signal filters each tuned to the frequency of one of said data signals, and further including means connected between said data signal filters for inhibiting the operation of one of said data signal filters when the other data signal filter is providing an output in response to receipt of its respective data signal.
 9. The control system of claim 8 wherein said last mentioned means includes first and second flipflop means each having one input connected to said input circuit and responsive to said enabling signal To be switched to a reset state, another input of said first flipflop means connected to the output of one of said data signal filter means, and another input of said second flipflop means connected to the output of said other data signal filter means, and wherein said detecting and decoding means further includes a decoder logic circuit for decoding the binary code represented by said data signals to provide an output signal for controlling an utilization device, and circuit means connecting the output of said first and second flipflop means to said decoder logic circuit.
 10. An acoustic control system comprising, in combination: transmitting means including signal generator means for providing a plurality of different acoustic signals, coding logic means for providing coded logic pulses in response to an operator command, combining means connected to said signal generator means and said coding logic means and responding to said coded logic pulses and said different acoustic signals to provide a coded control signal comprising said plurality of different acoustic signals in a coded sequence, and transmitting transducer means connected to said combining means for radiating said coded control signal including said different acoustic signals; and receiving means including an input circuit having receiving transducer means for receiving and responding to said radiated coded control signal, detecting means including a plurality of distinctive signal detecting circuits connected to said input circuit and each detecting circuit detecting and responding to one of said different acoustic signals of said coded control signal output signals, at least one of said detecting circuits adapted to be connected to a source of electrical energy to be normally operative and responding to the first received of said different acoustic signals comprising said coded control signal to provide an enabling signal, the remaining detecting circuits being normally in a stand-by condition, decoding means connected to said detecting means for decoding and acting on the coded control signal when detected by said detecting means, and power switch means adapted to be connected to a source of electrical energy and connected to said detecting means and said decoding means, said switch means responsive to said enabling signal to supply electrical energy to activate said decoding means and said remaining of said detecting circuits.
 11. The control system of claim 10 wherein said signal generating means provides said plurality of different acoustic signals at different audio frequencies, one of said different frequency signals representing a space tone and at least one other of said output signals representing a data tone; said combining means responds to said coding logic means to provide said coded control signal with a predetermined number of said space tones being transmitted at predetermined time intervals and with at least one data tone transmitted between successive space tones, and wherein said at least one of said detecting circuits is a space tone filter circuit tuned to substantially the frequency of said space tone, and each of said remaining of said detecting circuits is a data tone filter circuit tuned to substantially the frequency of a data tone.
 12. The control system of claim 11 wherein said coded control signal provides a binary code and two data tones of different frequencies are transmitted to represent respectively binary 1 and binary 0, and said detecting circuits comprises two data tone filter circuits each tuned to substantially the frequency of one of said data tones.
 13. The control system of claim 12 further including inhibit means connected between said data tone filter circuits for inhibiting the operation of one of said data tone filter circuits when the other data tone filter circuit is producing an output in response to receipt of its respective data tone.
 14. The control system of claim 11 further including delay means connected to said detecting means and to Said power switch means, said delay means responsive to said enabling signal to generate a delay signal having a duration at least as great as the interval between successive space tones, said power switch means responsive to said delay signal to stop the conduction of electrical energy to said decoder means and said data tone filter circuits to render them inoperative when a space tone is not received by said receiving means during the duration of said delay signal.
 15. The control system of claim 14 wherein said delay means includes a timer circuit connected to said power switch means, said timer circuit providing said delay signal in response to said enabling signal, and a monostable circuit connected between said space tone filter circuit and said timer circuit and responsive to received space tone signals to reset said timer circuit prior to the end of said delay signal.
 16. A remote control system, comprising, in combination: transmitting means including signal generator means for providing a plurality of different signals, coding logic means for providing coded logic pulses in response to an operator command, combining means connected to said signal generator means and said coding logic means and responding to said coded logic pulses and said different signals to provide a coded control signal comprising said plurality of different signals in a coded sequence, and transmitting transducer means connected to said combining means for radiating said coded control signal; and receiving means including an input circuit having receiving transducer means for receiving and responding to said radiated coded control signal, detecting means including a plurality of distinctive signal detecting circuits connected to said input circuit and each detecting circuit detecting and responding to one of said different signals of said received coded control signal, at least one of said detecting circuits adapted to be connected to a source of electrical energy to be normally operative and responding to the first received of said different signals comprising said coded control signal to provide an enabling signal, decoding means connected to said detecting means for decoding and acting on the coded control signal when detected by said detecting means, and power switch means adapted to be connected to a source of electrical energy and connected to said detecting means and said decoding means, said switch means responsive to said enabling signal to supply electrical energy to activate said decoder means and at least part of said detecting means. 